Bioelectronic Sensor Mesh: Growing with Heart Tissue

A groundbreaking project led by a team of engineers from the University of Massachusetts Amherst has set out to revolutionize the study of heart disease by instrumenting cardiac tissue grown outside the body. This innovative approach aims to gain a deeper understanding of the intricate mechanical and electrical activities of cardiac tissue, which play a crucial role in pumping blood throughout the body.

Jun Yao, a researcher from UMass Amherst's college of engineering, emphasized the uniqueness of cardiac tissue, stating, "Cardiac tissue is very special. It has a mechanical activity - contractions and relaxations that pump blood through our body - coupled to an electrical signal that controls that activity." This dual nature of cardiac tissue presents a complex yet fascinating challenge for researchers seeking to unravel the mysteries of heart function and dysfunction.

The focus of the project, termed 'cardiac micro-tissue,' lies in utilizing human stem cells to grow tissue that closely mimics the properties of natural cardiac tissue. To ensure the integrity of the tissue and avoid damage, the team needed to develop a method of integrating sensors into the tissue matrix during the growth process. This approach allows the tissue to develop without interference, paving the way for more accurate and reliable data collection.

The team's innovative solution involved designing graphene transistors measuring a mere 20 x 20μm, comparable in size to a cell, to monitor the excitation-contraction coupling within the cardiac micro-tissue. These transistors, with channels modulated by local electrical potentials, are capable of detecting both the self-generated electrical signals and the resulting mechanical movements within the tissue. Their unique piezo-resistive properties enable them to register even the slightest muscle contractions without impeding the heart's function.

By interconnecting the graphene transistors with a mesh of gold palladium conductors on a flexible substrate, the team created a soft, stretchable porous scaffold that closely resembles human tissue. This scaffold, insulated from the tissue sample by a layer of silicon nitride, offers a non-invasive method of monitoring the cardiac micro-tissue throughout its maturation process. The flexibility and stretchability of the scaffold, combined with the longevity and conductivity of graphene, make it a game-changing tool for cardiac research.